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This project contains some of the configurable modules used within the Heritrix application to crawl the web. The modules in this project can be used in applications other than Heritrix, however.

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/*
 *  This file is part of the Heritrix web crawler (crawler.archive.org).
 *
 *  Licensed to the Internet Archive (IA) by one or more individual 
 *  contributors. 
 *
 *  The IA licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.archive.modules.net;

import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.apache.commons.collections.Closure;
import org.apache.commons.httpclient.URIException;
import org.archive.net.UURI;

/**
 * Abstract class for crawl-global registry of CrawlServer (host:port) and
 * CrawlHost (hostname) objects.
 */
public abstract class ServerCache {

    public abstract CrawlHost getHostFor(String host);

    public abstract CrawlServer getServerFor(String serverKey);

    /**
     * Utility for performing an action on every CrawlHost. 
     * 
     * @param action 1-argument Closure to apply to each CrawlHost
     */
    public abstract void forAllHostsDo(Closure action);

    
    private static Logger logger =
        Logger.getLogger(ServerCache.class.getName());
    
    /**
     * Get the {@link CrawlHost} associated with curi.
     * @param uuri CandidateURI we're to return Host for.
     * @return CandidateURI instance that matches the passed Host name.
     */
    public CrawlHost getHostFor(UURI uuri) {
        CrawlHost h = null;
        try {
            if (uuri.getScheme().equals("dns")) {
                h = getHostFor("dns:");
            } else if (uuri.getScheme().equals("whois")) {
                h = getHostFor("whois:");
            } else {
                h = getHostFor(uuri.getReferencedHost());
            }
        } catch (URIException e) {
            logger.log(Level.SEVERE, uuri.toString(), e);
        }
        return h;
    }

    /**
     * Get the {@link CrawlServer} associated with curi.
     * @param uuri CandidateURI we're to get server from.
     * @return CrawlServer instance that matches the passed CandidateURI.
     */
    public CrawlServer getServerFor(UURI uuri) {
        CrawlServer cs = null;
        try {
            String key = CrawlServer.getServerKey(uuri);
            // TODOSOMEDAY: make this robust against those rare cases
            // where authority is not a hostname.
            if (key != null) {
                cs = getServerFor(key);
            }
        } catch (URIException e) {
            logger.log(
                Level.FINE, "No server key obtainable: "+uuri.toString(), e);
        } catch (NullPointerException npe) {
            logger.log(
                Level.FINE, "No server key obtainable: "+uuri.toString(), npe);
        }
        return cs;
    }

    abstract public Set hostKeys();


}